1. Field of the Invention
The present invention relates to a stationary induction electric apparatus such as a transformer or an iron-core reactor, and in particular, to a winding cooling structure.
2. Description of the Related Art
In a stationary induction electric apparatus configured of an iron core, a winding wound around the leg of core, and a plurality of cylindrical insulation structures, heat generated by electrification in the winding is transmitted to the coolant circulating around, and is discharged to the outside air or the like from a radiator or the like. This means that the winding is cooled. There are a case where coolant is forcibly circulated by a pump or the like (hereinafter referred to as forced convection) and a case where coolant circulates due to a temperature rise in the coolant around the winding (hereinafter referred to as natural convection).
In the case where a wire is wound a large number of times to constitute a winding, there is a structure in which the wire is arranged adjacently in a radial direction to produce a disk-like winding element (hereinafter referred to as a coil), and a plurality of them are arranged in an axial direction. In the case of cooling such a winding, as the flow velocity of the coolant differs depending on the position of the wire constituting the coil, heat transmission from the wire to the coolant may differ depending on the position.
In order to make heat transmission uniform in a circumferential direction of the coil mainly, there is a method in which a flow in vertical ducts (flow channel) formed between the winding and cylindrical insulation structures arranged on both sides thereof is sealed so as to form an almost zigzag flow from the inner side to the outer side or from the outer side to the inner side of the winding.
However, in the case of cooling the winding, as described, above, by natural convection, as the flow velocity of the circulating coolant is lower compared with the case of forced convection, there is a problem that the flow velocity of the coolant is likely to vary in the vicinity of respective portions of the winding. In order to cool the winding efficiently, it is desirable to make the flow velocity of the coolant uniform in respective portions of the winding.
As background art of the present technical field, there is JP-07-014723-A. JP-07-014723-A describes a structure in which in a winding having interval spacer plates for sealing the flow in a vertical flow channel to form a zigzag flow, the interval space plates are provided at narrower intervals in the upper portion of the winding and at wider intervals in the lower portion of the winding. There is also JP-2012-119639-A. JP-2012-119639-A describes a structure in which a transformer winding is divided into two, and blockage plates for blocking inner and outer side vertical channels and releasing the center vertical cooling channel and blockage plates for blocking the center vertical cooling channel are alternately arranged in an axial direction. There is also JP-09-199345-A. JP-09-199345-A describes a structure in which a flow dividing plate is provided to narrow the flow channel in the game direction as the downstream side of the opening of a baffle, and on the downstream side of the flow dividing plate, a flow return plate is provided on the vertical duct side opposite to the opening.